A conventional watering nozzle generally includes a handle connected with a hose so that water enters into the handle and a valve assembly is received in the handle and the valve assembly is cooperated with the trigger which can be pulled to activate the valve assembly to allow the water to flow through the barrel of the watering nozzle. One of the trigger mechanisms used on the watering nozzles includes a gear which is movably connected to the trigger and an engaging plate with toothed periphery can be movably engaged with the gear by pulling the trigger. By the engagement of the engaging plate and the gear, the user may control the volume of water entering the nozzle. However, the engaging plate and the gear are received in the handle and the user cannot see them so that when pulling the trigger to engaging the engaging plate with the gear, the users cannot be sure whether or not that the engaging plate is matched with the gear as desired. Sometimes, the users have to engage the engaging plate and the gear by way of try and error. The gear might be shifted by the movement of the engaging plate. Besides, the engaging plate is a thin plastic plate which might be deformed and cannot be perfectly engaged with the gear.